libspf2 is a library that implements the Sender Policy Framework,
allowing mail transfer agents to make sure that an email is authorized
by the domain name that it is coming from. Currently, only the exim MTA
uses libspf2 in Gentoo.

libspf2 uses a fixed-length buffer to receive DNS responses and does
not properly check the length of TXT records, leading to buffer
overflows.

Impact

A remote attacker could store a specially crafted DNS entry and entice
a user or automated system using libspf2 to lookup that SPF entry (e.g.
by sending an email to the MTA), possibly allowing for the execution of
arbitrary code.